大麦哲伦星系诱导的银河系晕扰动II：弥合场级推断与基于总结级模拟的推断
LMC-induced Perturbations in the Milky Way Halo II: Bridging Field-level Inference and Summary-level Simulation-Based Inference
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中文总结 AI 辅助
研究银河系与大麦哲伦星系引力作用下晕扰动相关问题，通过比较场级似然基准与可解释总结，利用CFM模型、BFE及MOPED算法，建立联合推断管道，有效收紧边际约束，为MW - LMC推断提供新途径并界定信息内容。
中文摘要 AI 辅助
银河系（MW）与大麦哲伦星系（LMC）之间的引力相互作用使外晕进入动力学不平衡状态，将两个星系的质量和结构参数印刻在晕示踪剂的6维相空间分布上。该信号已通过从低阶速度矩到基函数展开的总结统计进行了表征，但这些总结丢弃了多少信息以及它们是否互补仍不清楚。我们通过比较场级似然基准与用于约束（$M_{\mathrm{MW}}$，$M_{\mathrm{LMC}}$，$c$，$q$）的物理可解释总结来解决这些问题，其中$c$和$q$是MW晕的浓度和扁平率。在HaloDance N体套件上训练的条件流匹配（CFM）模型在一个保留的基准点提供了精确的似然；对于30 - 120 kpc内的5000个示踪剂，它比全天空速度矩预测将边际约束收紧了2.5 - 9.9倍。然后，我们在多极基函数展开（BFE）中扩展晕密度和速度场，并使用大规模优化参数估计和数据压缩（MOPED）算法将系数压缩为四个对参数敏感的总结，这些总结保留了它们的费舍尔信息。变分互信息分析表明，BFE + MOPED总结和速度矩是互补的，因此我们将它们组合成一个联合的19维向量作为我们的主要推断管道：它比单独的BFE + MOPED将边际约束收紧了高达15%，比单独的速度矩收紧了30 - 71%，达到了场级基准的1.3 - 2.9倍。因此，我们建立了一条物理可解释的总结级路线来进行MW - LMC推断，同时还有界定其信息内容的场级基准。
英文摘要
The gravitational interaction between the Milky Way (MW) and the Large Magellanic Cloud (LMC) drives the outer halo into dynamical disequilibrium, imprinting the masses and structural parameters of both galaxies onto the 6D phase-space distribution of halo tracers. This signal has been characterised with summary statistics ranging from low-order velocity moments to basis function expansions, yet how much information these summaries discard, and whether they are complementary, remains unclear. We address these questions by comparing a likelihood of the halo phase-space distribution (field-level) with physically interpretable summaries for constraining $(M_{\mathrm{MW}}, M_{\mathrm{LMC}}, c, q)$, where $c$ and $q$ are the MW halo concentration and flattening. A Conditional Flow Matching (CFM) model trained on the HaloDance $N$-body suite provides an exact likelihood at a held-out fiducial point; for 5,000 tracers in $30$--$120$~kpc it tightens marginal constraints by factors of $2.5$--$9.9$ over an all-sky velocity-moment forecast. To narrow this gap, we construct four parameter-sensitive summaries via BFE+MOPED that capture the angular structure of the halo density and velocity and contain information complementary to the velocity moments. Combining the two sets of summaries tightens the marginal constraints by up to $15$ per cent relative to the angular summaries alone, and by $30$--$71$ per cent relative to the velocity moments alone, although the resulting constraints remain $1.3$--$2.9$ times broader than those from the full phase-space benchmark. We thus establish a physically interpretable summary-level route for applying this inference pipeline to future observations, while the field-level benchmark measures the information available for further improvement.
发表机构
- Research School of Astronomy and Astrophysics, Australian National University（澳大利亚国立大学天文学与天体物理研究学院）
- Department of Astronomy, The Ohio State University（俄亥俄州立大学天文学系）
- Center for Cosmology and AstroParticle Physics (CCAPP), The Ohio State University（俄亥俄州立大学宇宙学与亚原子粒子物理中心）
- Max-Planck-Institut für Astronomie（马克斯·普朗克天文学研究所）
- National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）
- Institute for Frontiers in Astronomy and Astrophysics, Beijing Normal University（北京师范大学前沿天文与天体物理研究所）
- School of Engineering, Westlake University（西湖大学工程学院）
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